Hair cosmetic composition

ABSTRACT

Provided is a leave-on hair cosmetic composition, which contains the following components (A) and (B): (A) an organic C 2-8  dicarboxylic acid or salt thereof, and (B) at least one of more of an organic solvent selected from the group consisting of aromatic alcohols, N-alkylpyrrolidones, alkylene carbonates, polypropylene glycols, lactones and cyclic ketones, wherein the organic solvent has a C log P of from −2 to 3; and wherein the cosmetic composition has a pH of from 2 to 5 at 25° C. when diluted to 20 times the weight with water and has a buffering capacity of 0.001 gram equivalent/L or greater but less than 0.2 gram equivalent/L. The present invention also relates to a hair quality improving method which comprises treating the hair with the hair cosmetic composition. The hair cosmetic composition of the present invention can provide benefits such as luster, manageability, pliability and elasticity to the hair which is apt to be dry, having lost water therefrom owing to damage by coloring, permanent waving, or repetitive excessive blow drying.

FIELD OF THE INVENITON

The present invention relates to a leave-on hair cosmetic composition containing an organic dicarboxylic acid or salt thereof.

BACKGROUND OF THE INVENTION

In recent years, it has been said that owing to the influence of chemical treatment such as hair coloring or physical treatment by blow drying, cuticles on the hair surface peel off or the hair becomes porous by the efflux of lipids from the inside of the hair and as a result, the hair inevitably becomes excessively dry, resistant to finger combing, difficult to style and is unmanageable and lusterless.

Examples of commercially available leave-on hair cosmetic compositions mainly used now are emulsion type products such as hair cream having wax, higher alcohol and surfactant to provide the hair with manageability and protect the hair from excessive drying; and gel products having a film forming polymer (set polymer) incorporated therein. Such hair cosmetic compositions can temporarily overcome the problems such as poor manageability and excessive dryness by causing oil or fat or a polymer to adhere to the hair surface, thereby forming a film structure, but cannot fundamentally improve the hair luster or manageability.

Some hair cosmetic compositions for improving the hair quality are known. Of these, compositions using a specific organic acid and organic solvent are known as those using a technology intended to improve hair quality by acting on the inside of the hair (refer to, for example, JP-A-1995-112921, JP-A-1994-172131, JP-A-1997-301831 and JP-A-1994-298625). These compositions promote manageability of the hair by softening the hair which is stiff and therefore, hard to handle.

SUMMARY OF THE INVENTION

In the present invention, there is thus provided a leave-on hair cosmetic composition, which contains the following components (A) and (B):

-   -   (A) an organic C₂₋₈ dicarboxylic acid or salt thereof, and     -   (B) at least one or more of an organic solvent selected from the         group consisting of aromatic alcohols, N-alkylpyrrolidones,         alkylene carbonates, polypropylene glycols, lactones and cyclic         ketones, wherein the organic solvent has a C log P of from −2 to         3; wherein the cosmetic composition has a pH of from 2 to 5 at         25° C. when diluted to 20 times the weight with water and has a         buffering capacity of 0.001 gram equivalent/L or greater but         less than 0.2 gram equivalent/L.

In another aspect of the invention, there is also provided a hair quality improving method, which includes treating the hair with the above-described composition.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to a leave-on hair cosmetic composition capable of benefits such as essentially improving the hair quality, improving luster and manageability of the hair, and providing excellent feel of the hair.

In the present invention, the term “hair quality improvement” means improvement of strength/body, manageability and feel of the hair. The present inventors have completed the present invention upon finding that giving a certain buffering capacity to a hair cosmetic composition containing an organic dicarboxylic acid and a penetration-promoting organic solvent enables the resulting composition to maintain a stable performance and strong resistance against environmental changes upon use (for example, when applied to wet hair), promotes the penetration of the organic dicarboxylic acid and organic solvent into the hair, and gives further improved strength/body and manageability to the hair as well as improved feel of the hair.

The organic dicarboxylic acid to be used as Component (A) of the invention has from 2 to 8 carbon atoms and examples thereof include malonic acid, succinic acid, glutaric acid, adipic acid, maleic acid, fumaric acid, phthalic acid, oxalic acid, malic acid and tartaric acid. Of these, those having at least 3 carbon atoms, especially hydroxydicarboxylic acids such as malic acid and tartaric acid, and malonic acid and succinic acid are preferred. Malic acid is more preferred. Examples of the salts of these organic dicarboxylic acids include salts with an alkali metal, alkaline earth metal, ammonia and organic amine compound.

These compounds serving as Component (A) may be used in combination of two or more. The content of Component (A) in the hair cosmetic composition of the invention is preferably from 0.01 to 30 wt. %, more preferably from 0.1 to 20 wt. %, even more preferably from 0.5 to 10 wt. % in consideration of internal hair-quality improving effects (pore repairing effects and the like), set retention improving effects and manageability improving effects.

The organic solvent to be used as Component (B) of the invention is at least one or more selected from the group consisting of aromatic alcohols, N-alkylpyrrolidones, alkylene carbonates, polypropylene glycols, lactones and cyclic ketones. Preferable examples are those selected from the following (b1) to (b5).

-   -   (b1) Aromatic alcohols represented by the formula (1):         wherein, R¹ represents a group R²-Ph-R³— (R²: a hydrogen atom, a         methyl group or a methoxy group, R³: a bond or a saturated or         unsaturated divalent C₁₋₃ hydrocarbon group, Ph: paraphenylene         group), Y and Z each represents a hydrogen atom or a hydroxy         group, and p, q and r each stands for an integer of from 0 to 5,         with the proviso that at p=q=0, Z does not represent a hydrogen         atom and R¹ does not represent a group R²-Ph-.     -   (b2) N-alkylpyrrolidones having a nitrogen atom to which a C₁₋₁₈         alkyl group is bonded.     -   (b3) C₂₋₄ Alkylene carbonates.     -   (b4) Polypropylene glycols having a number average molecular         weight of from 100 to 1000.     -   (b5) Lactones or cyclic ketones represented by any one of the         formulas (2), (3) and (4):         wherein, X represents a methylene group or an oxygen atom, R⁴         and R⁵ represent substituents which are different from each         other, and a and b each stands for 0 or 1.

Of the organic solvents serving as Component (B), examples of (b1) include benzyl alcohol, cinnamyl alcohol, phenethyl alcohol, p-anisyl alcohol, p-methylbenzyl alcohol, phenoxyethanol, and 2-benzyloxyethanol; those of (b2) include N-methylpyrrolidone, N-octylpyrrolidone and N-laurylpyrrolidone; and those of (b3) include ethylene carbonate and propylene carbonate. As the polypropylene glycol (b4) having a number average molecular weight of from 100 to 1000, those having a number average molecular weight of from 100 to 500 are preferred, with those having a polymerization degree of from 2 to 5 being more preferred. For (b5), R⁴ and R⁵ in formulas (2) to (4) are each preferably a linear, branched or cyclic alkyl group, hydroxy group, sulfonic acid group, phosphoric acid group, carboxy group, phenyl group, sulfoalkyl group, phosphoric acid alkyl group and carboxyalkyl group. Of these, linear or branched C₁₋₆ alkyl groups—such as methyl, ethyl, propyl, isopropyl and butyl—substituted at the γ position in the case of γ-lactone and substituted at the δ position (methylene adjacent to the hetero oxygen atom) in the case of δ-lactone are preferred. In order to enhance the water solubility of the compounds (2) to (4), R⁴ or R⁵ preferably represents an acid group such as sulfonic acid group, phosphoric acid group or carboxy group, or an alkyl group having such a group substituted therewith. For (b5), examples of the lactone include γ-butyrolactone, γ-caprolactone, γ-valerolactone, δ-valerolactone, δ-caprolactone and δ-heptanolactone. Of these, γ-lactone, especially γ-butyrolactone and γ-caprolactone are preferred in view of the stability of the lactone. Examples of the cyclic ketone as (b5) include cyclopentanone, cyclohexanone, cycloheptanone and 4-methylcycloheptanone.

Examples of preferred Component (B) include benzyl alcohol, benzyloxyethanol, propylene carbonate and propylene glycol (number average molecular weight of from 300 to 500, preferably 400).

Component (B) to be used in the invention is preferably liquid at 25° C. and has a C log P of from −2 to 3, preferably from −1 to 2 in view of promoting the penetration. The term “C log P” as used herein means a measure indicating the distribution of a substance between an octanol phase and an aqueous phase. It is a calculated value of an octanol-water distribution coefficient (log P) as defined by the below-described equation and its example is described in Chemical Reviews, 71(6), 1971. log P=log([Substance]_(octanol)/[Substance]_(water)) wherein, [Substance]_(octanol) means a mole concentration of a substance in a 1-octanol phase, while [Substance]_(water) means a mole concentration of the substance in an aqueous phase.

The followings are C log P of main compounds usable as Component (B): benzyl alcohol (1.1), 2-benzyloxyethanol (1.2), 2-phenylethanol (1.2), 1-phenoxy-2-propanol (1.1), polypropylene glycol 400 (0.9), propylene carbonate (−0.41), and Y-butyrolactone (−0.64).

As Component (B), two or more compounds may be used in combination. Its content in the hair cosmetic composition of the invention is preferably from 0.1 to 40 wt. %, more preferably from 0.5 to 10 wt. %, even more preferably from 1 to 5 wt. % in view of feeling upon use, hair luster and hair quality improving effects (e.g. improvement of elasticity, improvement of moisture resistance and the like).

A weight ratio (A):(B) of the organic dicarboxylic acid or salt thereof as Component (A) to the organic solvent as Component (B) preferably ranges from 10:1 to 1:7, more preferably from 4:1 to 1:3 in order to effectively develop internal hair-quality improving (pore repairing) effects, set retention improving effects and manageability improving effects.

The hair cosmetic composition of the invention may further contain ethanol. Ethanol contributes to the solubilization or stable dispersion of Component (B). The content of ethanol in the hair cosmetic composition of the invention is preferably from 0.01 to 50 wt. %, more preferably from 1 to 20 wt. %. A weight ratio of ethanol to Component (B) preferably ranges from 40:1 to 2:1, more preferably from 20:1 to 3:1 from the viewpoint of promoting penetration of Components (A) and (B) into the hair.

The hair cosmetic composition of the invention may further contain a set polymer in view of improvement of hair styling, regulation of viscosity, stability, improvement of adhesion upon application to the hair, improvement of feel of the hair and early expression of hair quality improving effects. Examples of such a polymer include polyvinylpyrrolidone polymer compounds such as polyvinylpyrrolidone, vinylpyrrolidone/vinyl acetate copolymer, vinylpyrrolidone/vinyl acetate/vinyl propionate tertiary copolymer, vinylpyrrolidone/alkylaminoacrylate (quaternized chloride) copolymer, vinylpyrrolidone/acrylate/(meth)acrylic acid copolymer, and vinylpyrrolidone/alkylaminoacrylate/vinylcaprolactam copolymer; acidic vinyl ether polymer compounds such as methyl vinyl ether/maleic anhydride alkyl half ester copolymer; acidic polyvinyl acetate polymer compounds such as vinyl acetate/crotonic acid copolymer, vinyl acetate/crotonic acid/vinyl neodecanoate copolymer and vinyl acetate/crotonic acid/vinyl propionate copolymer, acidic acrylic polymer compounds such as (meth)acrylic acid/(meth)acrylate copolymer, and acrylic acid/alkyl acrylate/alkylacrylamide copolymer; amphoteric acrylic polymer compounds such as N-methacryloylethyl-N,N-dimethylammonium-α-N-methylcarboxybetaine/butyl methacrylate copolymer, and hydroxypropyl acrylate/butylaminoethyl methacrylate/acrylic octylamide copolymer; basic acrylic polymer compounds such as acrylamide/acrylate quaternary copolymer; cellulose derivatives such as cationic cellulose derivative; and chitin/chitosan derivatives such as hydroxypropyl chitosan, carboxymethyl chitin, and carboxymethyl chitosan.

These set polymers may be used either singly or in combination of two or more. Their content in the hair cosmetic composition of the invention is preferably from 0.1 to 10 wt. %, more preferably from 0.5 to 5 wt. %.

In the hair cosmetic composition of the invention, at least one or more conditioning component selected from silicones and oily substances may be incorporated in order to improve conditioning effects further. Examples of the silicones include dimethylpolysiloxanes, polyether-modified silicones, amino-modified silicones, carboxy-modified silicones, methylphenylpolysiloxanes, fatty acid-modified silicones, alcohol-modified silicones, aliphatic alcohol-modified silicones, epoxy-modified silicones, fluorine-modified silicones, cyclic silicones, and alkyl-modified silicones. Of these, dimethylpolysiloxanes, polyether-modified silicones and amino-modified silicones are preferred. Dimethylpolysiloxanes, polyether-modified silicones and amino-modified silicones can impart the hair with good lubricity, smoothness and moist feel, respectively. In the invention, various silicones can be used either singly or in combination of two or more depending on the desired performance.

As the dimethylpolysiloxane, those having a viscosity of from 5 mm²/s to 10 million mm²/s can be used depending on the desired feel of the hair, wherein those having a viscosity of 10 million mm²/s are often supplied in the form of an emulsion. Of these, those having a viscosity falling within a range of from 5000 mm²/s to 10 million mm²/s are preferred, with those having a viscosity of from 50000 mm²/s to 10 million mm²/s being more preferred.

The term “polyether-modified silicones” is a generic name of polyoxyethylene/methylpolysiloxane copolymers and poly(oxyethylene/oxypropylene)methylpolysiloxane copolymers and those having various HLBs are known. Examples of the commercially available products thereof include “Silicone KF351A”, “Silicone KF353A”, “Silicone KF6008”, “Silicone KF6016”, “Silicone KF6011”, and “Silicone KF6012” (each, trade name; product of Shin-etsu Chemical), and “SH3771C”, “SH3773C”, and “SH3775C” (each, trade name; product of Dow Corning Toray Silicone). As the amino-modified silicones, amodimethicone oil or an emulsion thereof is preferred. Their commercially available products are amodimethicone emulsion “SM8704C” (trade name; product of Dow Corning Toray Silicone) and “KT-1989” and “XF-42-B1989” (each, trade name; product of GE Toshiba Silicones).

The content of the silicones in the hair cosmetic composition of the invention is preferably from 0.05 to 20 wt. %, more preferably from 0.1 to 10 wt. %, even more preferably from 0.5 to 5 wt. % in consideration of smoothness to facilitate finger combing and a stickiness-free feel.

The oily substance is added to improve the hair manageability after drying. Examples thereof include hydrocarbons such as squalene, squalane, liquid isoparaffin, light liquid paraffin, heavy liquid isoparaffin, α-olefin oligomer, liquid paraffin and cycloparaffin; glycerides such as castor oil, cacao oil, mink oil, avocado oil and olive oil; waxes such as bees wax, spermaceti, lanolin, microcrystalline wax, ceresin wax and carnauba wax; higher alcohols such as cetyl alcohol, oleyl alcohol, stearyl alcohol, isostearyl alcohol and 2-octyldodecanol; esters such as octyldodecyl myristate, hexyl laurate, cetyl lactate, propylene glycol monostearate, oleyl oleate, hexadecyl 2-ethylhexanoate, isononyl isononanoate and tridecyl isononanoate; higher fatty acids such as capric cid, lauric acid, myristic acid, palmitic acid, stearic acid, behenic acid, oleic acid, coconut oil fatty acid, isostearic acid and isopalmitic acid; and other oils such as isostearyl glyceryl ether and polyoxypropylene butyl ether. Of these, branched hydrocarbons including squalene, squalane, liquid isoparaffin, light liquid isoparaffin, heavy liquid isoparaffin, α-olefin oligomer are preferred.

The content of the oily substance in the hair cosmetic composition of the invention is preferably from 0.05 to 20 wt. %, more preferably from 0.1 to 10 wt. %, even more preferably from 0.5 to 5 wt. % in view of good manageability and stickiness-free feel.

In the hair cosmetic composition of the invention, a surfactant may be incorporated from the viewpoints of stability of the system including the solubilization or dispersion of the solvent, and improvement in the feel of the hair. As the surfactant, any one of cationic surfactant, nonionic surfactant, amphoteric surfactant and anionic surfactant can be used.

Examples of the cationic surfactant include quaternary ammonium salts represented by the following formula (6):

wherein R⁶ and R⁷ each independently represents a hydrogen atom, a C₁₋₂₈ alkyl group or a benzyl group, with the proviso that they do not simultaneously represent a hydrogen atom, a benzyl group or a C₁₋₃ lower alkyl group, and Z⁻ represents an anion.

Either one of R⁶ and R⁷ preferably represents an alkyl group having from 16 to 24 carbon atoms, more preferably 22 carbon atoms, even more preferably a linear alkyl group, while the other one represents a lower C₁₋₃ alkyl group, preferably a methyl group. Examples of the anion Z⁻ include halide ions such as chloride ions and bromide ions, and organic anions such as ethyl sulfate ions and methyl carbonate ions. Of these, halide ions are preferred, among which chloride ions are preferred.

As the cationic surfactant, mono(long chain alkyl) quaternary ammonium salts are preferred. Specific examples include cetyltrimethylammonium chloride, stearyltrimethylammonium chloride, arachyltrimethylammonium chloride and behenyltrimethylammonium chloride. Of these, stearyltrimethylammonium chloride and behenyltrimethylammonium chloride are more preferred.

Examples of the nonionic surfactant include polyoxyalkylene alkyl ethers, polyoxyalkylene alkenyl ethers, higher fatty acid sucrose esters, polyglycerin fatty acid esters, higher fatty acid mono- or di-ethanolamides, polyoxyethylene hydrogenated castor oils, polyoxyethylene sorbitan fatty acid esters, polyoxyethylene sorbitol fatty acid esters, alkyl saccharide surfactants, alkylamine oxides, and alkylamide amine oxides. Of these, polyoxyalkylene alkyl ethers, polyoxyethylene hydrogenated castor oil are preferred, with polyoxyethylene alkyl ethers being more preferred.

As the amphoteric surfactant, imidazoline, carbobetaine, amidobetaine, sulfobetaine, hydroxysulfobetaine, and amidosulfobetaine can be used.

Examples of the anionic surfactant include alkylbenzene sulfonates, alkyl or alkenyl ether sulfates, alkyl or alkenyl sulfates, olefin sulfonates, alkane sulfonates, saturated or unsaturated fatty acid salts, alkyl or alkenyl ether carboxylates, α-sulfone fatty acid salts, N-acylamino acid surfactants, mono- or di-phosphate surfactants and sulfosuccinates. Examples of the counterion as the anionic residue of the above-described surfactants include alkali metal ions such as sodium ion and potassium ion; alkaline earth metal ions such as calcium ion and magnesium ion, ammonium ions, alkanolamines having 1 to 3 alkanol groups with 2 or 3 carbon atoms (such as monoethanolamine, diethanolamine, triethanolamine and triisopropanolamine). Examples of the counterion as the cationic residue include halide ions such as chloride ions, bromide ions and iodide ions, methosulfate ions and saccharinate ions.

Of these, cationic surfactants are preferred in view of feel of the hair. These surfactants may be used either singly or in combination of two or more. The content of the surfactant(s) in the hair cosmetic composition of the invention is preferably from 0.01 to 10 wt. %, more preferably from 0.05 to 3 wt. % in view of stabilization of the system including solubilization of the solvent and emulsification of the oily substance.

The hair cosmetic composition of the invention may further contain a polyhydric alcohol. The polyhydric alcohol contributes to solubilization and stable dispersion of Component (B). In addition, the enhancement of the hair quality improving effect is accelerated by the synergistic action between the polyhydric alcohol and Component (B). Examples of the polyhydric alcohol include ethylene glycol, glycerin, sorbitol, propylene glycol, 1,3-butyleneglycol and dipropylene glycol. Of these, glycerin is preferred. These polyhydric alcohols may be used either singly or in combination of two or more. Its content in the hair cosmetic composition of the invention is preferably from 0.1 to 10 wt. %, more preferably from 0.5 to 5 wt. %.

The hair cosmetic composition of the invention may further contain, as needed, components employed for ordinary hair cosmetic compositions depending on their purpose of use. Examples of such components include antidandruffs, vitamin preparations, bactericides, anti-inflammatories, antiseptics, chelating agents, humectants such as sorbitol and panthenol, coloring agents such as dyes and pigments, viscosity regulators such as hydroxyethyl cellulose, methyl cellulose, polyethylene glycol and clay mineral, pH regulators such as sodium hydroxide and potassium hydroxide, plant extracts, pearling agents, perfumes, colorants, ultraviolet absorbers, antioxidants, and the other components as described in ENCYCLOPEDIA OF SHAMPOO INGREDIENTS (MICELLE PRESS).

The hair cosmetic composition of the invention is adjusted to have a pH of from 2 to 5 (at 25° C. when diluted to 20 times the weight with water), preferably from 2.5 to 4, more preferably from 3 to 4 upon application to the hair for the expression of the performances of the composition, for example, to improve the strength, body and luster of the hair and to give flexibility, manageability and pliability to the hair. Use of sodium hydroxide or potassium hydroxide is preferred to adjust the pH to fall within the above-described range.

Moreover, to control a change in pH upon application to the hair, accelerate the penetration of the organic acid and organic solvent to the hair, cause the hair quality improving effects to appear promptly and improve the feeling of effect, the hair cosmetic composition of the invention has a buffering capacity, as a 5 wt. % aqueous solution, of 0.001 gram equivalent/L or greater but less than 0.2 gram equivalent/L, preferably from 0.003 gram equivalent/L or greater but less than 0.1 gram equivalent/L, more preferably from 0.005 gram equivalent/L or greater but less than 0.05 gram equivalent/L. The term “buffering capacity” as used herein means a value determined from the below-described equation with, as a scale, the concentration of a base necessary for raising the pH at 25° C. of a 5 wt. % aqueous solution by 1 from the initial pH. Buffering capacity=|dC _(B) /dpH| wherein, C_(B) represents the ion concentration (gram equivalent/L) of a base.

Such a buffering capacity can be given to the hair cosmetic composition by adding thereto a pH buffering agent. As the pH buffering agent, organic acids or inorganic acids, or salts thereof having a buffering action within a pH range of from 2 to 5 can be employed. Examples of the organic acid include, in addition to those described in Component (A), citric acid, revulinic acid, butyric acid, valeric acid and mandelic acid; those of the inorganic acid include phosphoric acid, sulfuric acid and nitric acid; and the salt of these acids include alkali metal salts such as sodium salt and potassium salt, ammonium salts, and alkanolamine salts such as triethanolamine salt. No particular limitation is imposed on the amount of the buffering agent and it varies depending on the kind of the compound used to give a buffering capacity. For example, when sodium citrate is mainly used as a compound for giving a buffering capacity, it is added in an amount of about 1 wt. % or greater.

The form of the hair cosmetic composition of the invention can be selected from liquid, gel, paste, cream and wax as needed, but that in the form of a solution using, as a solvent, water is preferred.

The hair cosmetic composition of the invention is preferably used as a hair styling agent or hair conditioning agent. It can be provided, for example, as a pump spray, aerosol spray, pump foam, aerosol foam, gel or lotion.

By heating after application of the hair cosmetic composition of the invention to the hair, penetration of Components (A) and (B) into the hair can be accelerated. For heating, a drier, heater or hair iron can be used. The heating temperature is preferably 60° C. or greater, more preferably 70° C. or greater.

EXAMPLES

The present invention will hereinafter be described in further detail by examples. It should however be borne in mind that the present invention is not limited to or by them.

The pH in the below-described example and comparative composition is a value at 25° C. when diluted to 20 times the weight with water.

Example 1

Hair cosmetic compositions as shown in Table 2 were prepared and their “setting property”, “strength/body improving effect”, “manageability”, “feel of the hair” and “luster” were evaluated. The results are shown in Table 2.

(Evaluation Method)

Evaluation of “Setting Property”

1) Hair Bundle to be Evaluated

A hair bundle of 10 cm in length, 1.5 cm in width and 1 g in weight was made using the hair of a Japanese female whose hair has not been subjected to chemical treatment such as permanent waving or hair coloring. The hair bundle was bleached (by “Ravenus Color Appeal Inazuma Bleach”; product of Kao) twice and the resulting hair bundle was provided for the evaluation of setting property.

2) Treatment of the Hair Bundle

Pre-Shampoo Evaluation (Treatment 7 Times)

The hair bundle to be evaluated was subjected to shampooing (with “Ravenus Designing Shampoo”, product of Kao), towel drying, uniform application of 0.1 g of the invention product or comparative product (which will hereinafter be called “treatment agent”), and drying for 10 minutes with hot air of 70° C. This treatment procedure was repeated six times in total. After the hair bundle was shampooed, then towel dried and treated with the treatment agent in a similar way described above, it was wound around a rod having a diameter of 4 cm and dried for 10 minutes with hot air of 70° C.

Post-Shampoo Evaluation

The internal hair-quality improving effect was studied by evaluating the set retention after the treatment agent on the hair surface was washed away. After completion of the pre-shampoo evaluation, each hair bundle was shampooed and towel dried. Without application of the treatment agent to the hair, the hair bundle was wound around a rod having a diameter of 4 cm and dried for 10 minutes with hot air of 70° C.

3) Procedures and Criteria of Evaluation

The curled hair bundle was removed from the rod and a comb (ring comb) was run through the bundle 20 times to disentangle it. It was suspended in a thermo-hydrostatic box (25° C. and 98% RH) to determine the set retention power. Described specifically, the length of the hair bundle thus suspended (distance from the bundled position to the end of the hair) was measured. The length of the hair bundle right after suspension was set as set-retention percentage of 100% and the initial length of the hair bundle (10 cm) before curling was set as set-retention percentage of 0%. A relative value (%) of the length of the hair bundle after 30 minutes, that is, a set-retention percent after 30 minutes was determined in accordance with the following equation: Set retention (%)=((initial length of the hair bundle)−(length of the hair bundle after 30 minutes))/((initial length of the hair bundle)−(length of the hair bundle right after curling))×100

Evaluation of “strength/body improving effect”, “manageability”, “feel of the hair (smoothness, moistness, softness, stiffness, stickiness)” and “luster”

1) Hair Bundle to be Evaluated

A hair bundle of 25 cm in length and 6 g in weight was made using the hair of a Japanese female whose hair had not been subjected to chemical treatment such as permanent waving or hair coloring. The hair bundle was bleached (by “Ravenus Color Appeal Inazuma Bleach”; product of Kao) twice and the resulting hair bundle was provided for the evaluation.

2) Treatment of the Hair Bundle

Pre-Shampoo Evaluation

The hair bundle to be evaluated was subjected to shampooing (with “Ravenus Designing Shampoo”, product of Kao), towel drying, uniform application of 0.6 g of the treatment agent, and drying for 10 minutes with hot air of 70° C. while running a ring comb through the hair bundle. This treatment procedure was repeated seven times in total.

Post-Shampoo Evaluation

In order to study the internal hair-quality improving effect, the hair bundle after completion of the pre-shampoo evaluation was shampooed and towel-dried, and then dried for 10 minutes with hot air of 70° C. while running a ring comb through the hair bundle.

3) Evaluation Criteria

Organoleptic evaluation by a panel of 5 experts was performed in accordance with the criteria shown in Table 1 and an average of the scores is shown in Table 2. TABLE 1 (Strength/body improving effects) (Manageability) 5: Obvious improvement in strength/body 5: Excellent manageability 4: Improvement in strength/body 4: Some manageability 3: Some improvement in strength/body 3: Cannot be said either 2: Only slight improvement in 2: A little inferior in   strength/body   manageability 1: No improvement in strength/body 1: Lack of manageability (Feel of the hair: smoothness) (Feel of the hair: moist feel) 5: Very Smooth 5: Very moist 4: Smooth 4: Moist 3: Cannot be said either 3: Cannot be said either 2: Slightly smooth 2: Slightly moist 1: Not smooth 1: Not moist (Feel of the hair: softness) (Feel of the hair: stiffness) 5: Very soft 5: Not stiff 4: Soft 4: Slightly stiff 3: Cannot be said either 3: Cannot be said either 2: Slightly soft 2: Stiff 1: Not soft 1: Very stiff (Feel of the hair: stickiness) (Luster) 5: Not sticky 5: Marked improvement in   luster 4: Slightly sticky 4: Improvement in luster 3: Cannot be said either 3: Cannot be said either 2: Sticky 2: No improvement in luster 1: Very sticky 1: Loss of luster

TABLE 2 Example Comparative composition composition 1 1 Composition Malic acid 5.0 0.01 (wt. %) 2-Benyloxyethanol 2.5 2.5 Ethanol 10.0 10.0 Water Balance Balance Sodium hydroxide 0.75 — (pH buffer) pH (25° C., when diluted to 20 times the 3.7 3.4 weight with water) Buffering capacity 0.006 g/L 0.0005 g/L Pre-shampoo Set retention (%) 84 36 evaluation Strength/body improving 4.4 1.8 effects Manageability 4.0 2.0 Smoothness 3.8 1.6 Moist feel 3.8 2.2 Softness 4.2 3.0 Stiffness 4.2 4.0 Stickiness 4.0 4.2 Luster 4.2 1.8 Post-shampoo Set retention (%) 72 33 evaluation Strength/body improving 4.0 1.8 effect Manageability 3.2 2.0

The above-described results have revealed that unlike hair cosmetic compositions obtainable by the conventional technology that has not overcome the problems such as stiffness and stickiness, the example composition according to the invention achieved providing a good set retention, strength/body improving effects, manageability and improved feel of the hair. Even after the removal of the components attached to the surface of the hair by shampooing, the above-described effects last. In addition, the hair quality improving effects such as elimination of pores inside of the hair were confirmed.

Example 2 Pump Spray

(wt. %) Malic acid 4.0 Stearyltrimethylammonium chloride  0.25 Glycerin 1.0 2-Benzyloxyethanol 2.5 Ethanol 4.5 Perfume  0.02 Water Balance Citric acid 1.1 Sodium hydroxide (pH regulator) Amount to adjust pH to 3.7 [buffering capacity = 0.006 gram equivalent/L]

Example 3 Pump Mist

(wt. %) Malic acid 3.5 Malonic acid 1.0 2-Benzyloxyethanol 2.5 Polyvinylpyrrolidone 3.0 Ethanol 10.0  Perfume  0.05 Water Balance Sodium hydroxide (pH regulator) Amount to adjust pH to 3.7 [buffering capacity = 0.005 gram equivalent/L]

Example 4 Hair Gel

(wt. %) Malic acid 2.5 Succinic acid 1.5 Glycerin 2.0 2-Benzyloxyethanol 2.5 Hydroxyethyl cellulose 2.0 Ethanol 10.0  Perfume  0.05 Water Balance Potassium hydroxide (pH regulator) Amount to adjust pH to 3.7 [buffering capacity = 0.005 gram equivalent/L]

Example 5 Hair Lotion

(wt. %) Malic acid 4.0 Lactic acid 1.0 Glycerin 1.0 2-Benzyloxyethanol 2.5 Ethanol 10.0  Perfume  0.02 Water Balance Sodium hydroxide (pH regulator) Amount to adjust pH to 3.7 [buffering capacity = 0.006 gram equivalent/L]

Example 6 Hair Lotion

(wt. %) Malic acid 2.5 Lactic acid 1.5 Tartaric acid 1.0 Stearyltrimethylammonium chloride 0.1 Benzyl alcohol 2.0 Polyethylene glycol 400  0.45 Ethanol 4.5 Water Balance Sodium hydroxide (pH regulator) Amount to adjust pH to 3.7 [buffering capacity = 0.008 gram equivalent/L]

Example 7 Pump Foam

(wt. %) Malic acid 2.5 Succinic acid 2.5 Polyoxyethylene lauryl ether (16E.O.) 1.0 Stearyltrimethylammonium chloride 0.1 Glycerin 1.0 2-Benzyloxyethanol 2.0 Ethanol 4.0 Perfume  0.02 Water Balance Sodium hydroxide (pH regulator) Amount to adjust pH to 3.7 [buffering capacity = 0.007 gram equivalent/L] 

1. A leave-on hair cosmetic composition, comprising the following components (A) and (B): (A) an organic C₂₋₈ dicarboxylic acid or salt thereof, and (B) at least one or more of an organic solvent selected from the group consisting of aromatic alcohols, N-alkylpyrrolidones, alkylene carbonates, polypropylene glycols, lactones and cyclic ketones, wherein the organic solvent has a C log P of from −2 to 3; wherein the cosmetic composition has a pH of from 2 to 5 at 25° C. when diluted to 20 times the weight with water and has a buffering capacity of 0.001 gram equivalent/L or greater but less than 0.2 gram equivalent/L.
 2. The hair cosmetic composition of claim 1, further comprising a set polymer.
 3. The hair cosmetic composition of claim 1, further comprising at least one or more conditioning components selected from the group consisting of silicones and oily substances.
 4. The hair cosmetic composition of claim 1, further comprising a cationic surfactant.
 5. A hair quality improving method, which comprises treating the hair with a hair cosmetic composition of claim
 1. 